A Study on the Lime Reactivity of Concrete Admixtures

2002 ◽  
Vol 39 (5) ◽  
pp. 452-459 ◽  
Keyword(s):  
Concrete Admixtures ◽  
Lime Reactivity

scholarly journals Evolution of physicochemical properties of quick lime at converter-smelting temperature

2021 ◽  
Vol 40 (1) ◽  
pp. 32-39
Author(s):  
Mengxu Zhang ◽  
Jianli Li ◽  
Zhengliang Xue ◽  
Renlin Zhu ◽  
Qiqiang Mou ◽  
...  
Keyword(s):  
Boundary Migration ◽  
Average Diameter ◽  
Dissolution Behavior ◽  
Grain Boundary Migration ◽  
Average Pore ◽  
Quick Lime ◽  
Volume Stability ◽  
Steel Making ◽  
Dissolution Efficiency ◽  
Lime Reactivity

Abstract The volume stability caused by the hydration of f-CaO is one of the main obstacles to the comprehensive utilization of steel-making slag. In view of the f-CaO produced by incomplete dissolution of lime, it is necessary to strengthen the dissolution behavior of lime in the converter process. The reactivity of lime determines the dissolution efficiency and is closely related to its microstructure. The experimental results show that the reactivity and porosity of quick lime decrease and the average diameter of pore increases with an increase in temperature. The CaO crystals gradually grow up under the action of grain boundary migration. When the temperature increased from 1,350 to 1,600°C, the lime reactivity decreased from 237.60 to 40.60 mL, the porosity decreased from 30.55 to 15.91%, the average pore diameter increased from 159.10 to 1471.80 nm, and the average CaO particle size increased from 0.33 to 9.61 µm. The results indicate that reactivity is decreased because of the deformation and growth of CaO crystals and the decrease in porosity in reactive lime. This will cause an obstacle to the dissolution of lime and is not conducive to the control of f-CaO in slag.

scholarly journals Characterization of Gum Arabic As Viscosity Modifying Agent (VMA) for Producing Self-Compacting Concrete (SCC)

2021 ◽  
Vol 9 (2) ◽  
pp. 47-52
Author(s):  
Yousif Hummaida Ahmed ◽  
Moaz Ibrahim Rahamtalla ◽  
Khalid Salah Eldin
Keyword(s):  
Gum Arabic ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Acacia Senegal ◽  
Cement Ratio ◽  
Concrete Admixtures ◽  
Hot Weather ◽  
European Standards ◽  
Powder Content

This study aims at finding alternative indigenous Sudanese material for concrete admixtures that are necessary for casting concrete in hot weather of the Sudan. The objective of this study to classify Gum Arabic (GA) namely, Acacia Senegal (known locally as Hashab Gum) as viscosity modifying admixture (VMA) for lowering powder content in self compacting concrete (SCC). The methodology of the study is based on the European standards BS EN 934-2 & BS EN 480-15 that are used as a paradigm to classify GA as the VMA. Three trial SCC test mixes containing different quantity of cement, namely (400, 370 and 350) Kg/ as powder content. A dose of GA 0.2% by weight of cement is applied after being dissolved in water at a concentration of 30% by water weight. The water/cement ratio (W/C) is kept constant as 0.45 for all mixes. The results of this study showed that the 0.2% GA dosage is appropriate and satisfied all criteria set by BS EN 934-2: 2009 for VMA. Using 0.2% GA as VMA lower the powder of SCC from 400kg to 350kg/ while maintaining the SCC fresh properties.  

scholarly journals Research progress of key technologies for preparing concrete admixtures by multiple activation of iron-containing tailings

2020 ◽  
Vol 198 ◽  
pp. 03002
Author(s):  
Xiaowei Gu ◽  
Ziyang Hu ◽  
Peng Liu ◽  
Shuyun Pang ◽  
Haofeng Chi
Keyword(s):  
Environmental Pollution ◽  
Resource Utilization ◽  
Hot Spot ◽  
Research Progress ◽  
Social Concern ◽  
Concrete Admixtures ◽  
Key Technologies ◽  
Strength And Durability ◽  
Resource Shortage ◽  
Reasonable Use

Iron tailings are an excellent secondary resource. Reasonable use, it can not only alleviate the problem of resource shortage, but also solve some environmental pollution problems. Therefore, it has a good development prospect. The resource utilization of iron tailings has always been a hot spot of social concern. The article reviews the results achieved by the predecessors. In addition, outlines the method of activation of iron tailings and the influence of its strength and durability as a concrete composite admixture. At last, the prospects of the research on the utilization of iron tailings are put forward.

Synthesis and Effect of Polycarboxylate Superplasticizer with Two Different Molecular Polyethers as Side Chain

2012 ◽  
Vol 217-219 ◽  
pp. 578-581
Author(s):  
Shao Hu Zou ◽  
Wu Biao Duan ◽  
Xin Wang ◽  
Zhen Long Gao ◽  
Bo Liu
Keyword(s):  
Water Consumption ◽  
Reducing Agent ◽  
Side Chain ◽  
Side Chains ◽  
Polycarboxylate Superplasticizer ◽  
Single Side ◽  
Concrete Admixtures ◽  
Main Effect

Water-reducing agent was one of the most important concrete admixtures. Its main effect is to reduce the unit water consumption of concrete, increase strength, but also help to improve the durability, make it easy-to-mix. Water reducer has gone to polycarboxylate superplasticizer which has single side chain generally. A kind of new water reducer by choosing 2500 and 600 molecular polyethers as the side chains has the higher water-reducing effect than the traditional one. It is more than 26 on fluidity retention in 2 hours.

Concrete admixtures handbook

1986 ◽  
Vol 16 (5) ◽  
pp. 789
Author(s):  
Sidney Diamond
Keyword(s):  
Concrete Admixtures

A Generic Procedure for the Assessment of the Effect of Concrete Admixtures on the Sorption of Radionuclides on Cement: Concept and Selected Results

2003 ◽  
Vol 807 ◽  
Author(s):  
M. A. Glaus ◽  
A. Laube ◽  
L. R. Van Loon
Keyword(s):  
Screening Procedure ◽  
Concrete Admixtures ◽  
The Future ◽  
Selection Of

ABSTRACTA screening procedure is proposed for the assessment of the effect of concrete admixtures on the sorption of radionuclides on cement. The screening procedure focuses on a broad and generic assessment and can thus be used as a tool for the assessment of concrete admixtures possibly used in the future. The experimental feasibility of the screening procedure and the relevance of the results obtained are tested using a selection of superplasticisers and set modifiers. Selected results obtained for these admixtures are presented in this contribution.

On the Principle and Application of Concrete Admixtures

2012 ◽  
Vol 557-559 ◽  
pp. 805-808
Author(s):  
Tao Zhang ◽  
Yun Yun Xu ◽  
Lei Chen
Keyword(s):  
Development Prospect ◽  
Construction Technology ◽  
Classification Methods ◽  
Development Status ◽  
Concrete Admixtures ◽  
Working Principle ◽  
Early Strength ◽  
Future Direction ◽  
Air Entraining Agents

Widely used for concrete admixtures, the development status of concrete admixtures is summarized, the two classification methods of concrete admixtures are induced. Especially, currently mainly used four kinds of admixtures, water reducer, air entraining agents, retarders, and early strength agent, the working principle, the problem of construction application, the direction of development and construction technology are analyzed. Finally, admixture overall future direction of development prospect is presented.

scholarly journals Methodology for the economic evaluation of CO2 derived materials

Clean Energy ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 575-586
Author(s):  
Tiffany Wong ◽  
Dan Zilnik ◽  
Marcius Extavour ◽  
Michael Leitch
Keyword(s):  
Economic Evaluation ◽  
Co2 Emissions ◽  
Oil Sands ◽  
Economic Data ◽  
Data Set ◽  
Market Data ◽  
Concrete Admixtures

Abstract Scoring the technologies in competition for the NRG Canada’s Oil Sands Innovation Alliance Carbon XPRIZE required an economic evaluation to estimate the value created through the conversion of CO2 emissions into products. Across all of the Teams participating in the competition, 58 different materials were consumed and produced. Standardized prices and market sizes needed to be established for each of these materials to ensure a consistent evaluation across all Teams. The Standards Data Set (SDS) was created as a standardized database of economic data used in the competition. The rationale for the SDS project and the methodology for researching each material is described. Ultimately, credible material definitions using the SDS methodology were created for all materials, and some research and methodological customization were required for materials that did not have credible, publicly available market data. The methodologies for establishing credible values and market sizes for concrete, concrete admixtures and syngas are highlighted as examples of materials whose value and markets are not easily defined.

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